Juventus coach Massimiliano Allegri fears the use of video refereeing is turning football into a long-drawn out American sports extravaganza after the Serie A champions drew 2-2 at Atalanta.

Sunday’s game in Bergamo was dominated by the use of VAR — video assistant referee — once to cancel a Mario Mandzukic goal for Juventus and the second awarding the Turin side a contentious penalty after a handball.

“We’ll end up like baseball in the United States, where there are constant stoppages and we sit there eating nuts until the match ends at midnight,” complained Allegri after his side saw their winning run this season stalled.

“In my view, technology should only be used on objective situations – offside, in or out of the box, over the line or not – but when it comes to subjective situations, people are never going to agree. That’s sport.

“If we want football to be a sport that is no longer a sport, then use VAR on every incident.”

Juventus' forward from Colombia Juan Cuadrado (top) celebrates with Juventus' coach from Italy Massimiliano Allegri and Juventus midfielder Miralem Pjanic (R) after winning the Italian Serie A football match Juventus vs Crotone and the "Scudetto" at the Juventus Stadium in Turin. Photo: AFP

Juventus coach Massimiliano Allegri has labelled 11-time winners Real Madrid favourites for the Champions League final, but said the “optimistic” Italians intend on bringing the trophy home from Cardiff on Saturday.

Fresh from securing a record third consecutive league and Cup double, Juventus are looking to complete a treble this season when they face Real in the Welsh capital.

The June 3 final comes two years after a 3-1 defeat to Barcelona in Berlin in Allegri’s opening season at the club — that was Juve’s sixth defeat in the final of the competition, a record.

Real, meanwhile, won the trophy in 2014 and again last season, beating city rivals Atletico in the final on each occasion.

“We’re optimistic, but it doesn’t seem right to me that Juventus have been branded favourites because Real have won two Champions League titles in the past years,” Allegri said Monday.

“They’re used to playing the final, as we are. We have to accept that they are the favourites.”

Asked how this Juventus compares to his side two years ago, he added: “There’s more conviction. Since Berlin, we’ve grown a lot. Everyone, and that’s reassuring.

“We’re in the eye of the storm now, and we’re happy to be here. For me personally, getting to the final is a great joy. I will feel lucky when I sit in the dugout on Saturday.”

Asked if this would be the most important game of his career, Allegri said: “It’s the second, the first we lost in Berlin.

“This time we have to bring the trophy home, or, at least, create the conditions that allow us to.”

Juventus closed their domestic season on Saturday when teenage starlet Moise Kean came off the bench to hit a late winner at Bologna.

Having finished four points clear of second-placed Roma in Serie A, and won a record third consecutive Italian Cup with a comfortable 2-0 win over Lazio, Juve are now looking to emulate Inter Milan, Italy’s last treble winners in 2010 under Jose Mourinho.

“Finishing on 91 points isn’t easy, neither was winning the third (successive) Italian Cup, and it won’t be easy to win the Champions League,” Allegri said.

“We’re just missing the final piece, then we can go on holiday.”

Allegri has deployed a 4-2-3-1 formation in the second half of the season that has allowed Mario Mandzukic, Paulo Dybala and Juan Cuadrado to carve open opposition defences for Argentine striker Gonzalo Higuain.

And while he remained coy on whether tactical changes could be made for Saturday, defender Giorgio Chiellini underlined: “When it comes to defence, all 11 players are involved.

“The important thing is that everyone, from our strikers to our defence, makes sacrifices for each other.”

It will also be crucial, said Chiellini, for Juventus to avoid another tense start to the final that, two years ago, saw nerves creep in following a fourth-minute opener by Ivan Rakitic.

A potent new attacking formation that has sent Gonzalo Higuain towards another top scorer’s award faces the acid test Wednesday when Juventus take on Porto away in the last 16 of the Champions League.

Juventus, beaten 3-1 by Barcelona in the 2015 final, are en route to a record sixth Serie A crown and remain many pundits’ favourites to challenge the likes of Real Madrid for the trophy in Cardiff next May.

Massimiliano Allegri’s Serie A league leaders head to Porto’s Estadio do Dragao as favourites, but aware that they also ended Roma’s hopes of even qualifying for the competition in clinical fashion last summer.

“Juventus are a top side who have made it to the final of the Champions League recently, so they will be a challenge for us,” Porto president Pinto da Costa was quoted as saying in Corriere dello Sport.

“But Roma were also favourites against us, and in the end we won 3-0.”

Allegri’s decision to ditch his tried and trusted 3-5-2 for a more attack-minded 4-2-3-1 has seen Higuain, thanks to support from Juan Cuadrado, Paulo Dybala and Mario Mandzukic, pull level with Roma’s Edin Dzeko at the top of the Serie A charts on 19 goals so far.

But while the Juventus front line is firing on all cylinders, Porto have reason to be targeting a makeshift Juve defence that could be missing key components in Andrea Barzagli and Giorgio Chiellini.

Both remain doubtful due to recent injury niggles, meaning either Daniele Rugani or Mehdi Benatia could partner Leonardo Bonucci in central defence.

Allegri’s switch to a flat back four means Stephan Lichtsteiner, Dani Alves, Kwadwo Asamoah and Alex Sandro — who are all adept as wingbacks in a five-man midfeld — are all available for the left and right-back positions.

On Friday Allegri said: “Unless some strange things happen in the meantime, we will deploy a 4-2-3-1 in Portugal.”

Both Rugani and Lichtsteiner were completely rested for Friday’s 4-1 win over Palermo, in which Dybala hit a brace and Higuain hit one. Mario Mandzukic was also completely rested, suggesting he is a definite starter on Wednesday.

Allegri’s two holding midfielders are likely to be Miralem Pjanic, the side’s free-kick specialist, and Germany midfielder Sami Khedira. Italy international Claudio Marchisio, also on target against Palermo, is expected to start on the bench.

Porto might not be considered title winners, but Bonucci has done his homework.

“Maybe Porto aren’t among the favourites for the quarter-finals, but we will be giving them maximum respect,” the Italy defender told uefa.com.

“They went through a difficult period at the season but they’ve come bouncing right back in impressive fashion. They have some great young players and they’ll will playing with the mentality that they nothing to lose.

“If we want to stay in Europe, we’ll need a great performance on the night.”

Porto have hit 14 league goals in their past five league games, all wins, and former Portugal defender Jorge Andrade, who played for both clubs, says scoring an away goal will be crucial for the Italians.

“The most important thing for Juventus will be to be vigilant in Oporto, and to score a goal,” he told Tuttojuve.com.

“In Portugal people can’t wait for this match. Don’t forget that Porto have won the competition twice. Their key player will be (Tiquinho) Soares.”

Soares has hit four goals in three games since joining Porto last month and will be looking to make his mark in a game featuring two legendary goalkeepers in Iker Casillas and Gianluigi Buffon.